1. Field of the Invention
The present invention relates to a coil end structure of a rotating electric machine such as an electric motor, a generator or the like.
2. Description of the Related Art
Conventionally, there has been known a rotating electric machine provided with a stator and a rotor, such as an electric motor, a generator or the like (for example, refer to Patent Document 1: Published PCT International Application No. 2008/020471). As illustrated in FIG. 10, the stator in the rotating electric machine disclosed in Patent Document 1 is provided with a stator core 2′, a plurality of slots 2a′ disposed in the stator core 2′ in such a way that the plurality of slots 2a′ are disposed at intervals in the circumferential direction of the stator core 2′ and are configured to penetrate the stator core 2′ in the axial direction thereof, and a coil.
The coil is constructed by disposing a plurality of U-shaped coil segments 4′ having a pair of legs 41′, 41′ and a head 42′ joining the two legs 41′, 41′ at either one end portion of each leg 41′ in such a way that the legs 41′, 41′ pass through the slot 2a′ to project from the slot 2a′, and joining the corresponding projecting portions of the legs 41′, 41′ projecting from the slot 2a′. 
The coil segment 4′ is constructed from a bundle of a plurality of flat wires; and the head 42′ of the coil segment 4′ constitutes the coil end. According to the coil end in Patent Document 1, the adjacent flat wires are disposed to be aligned in the circumferential direction of the stator core 2′ in an attempt to miniaturize the coil end.
The U-shaped flat wire constituting the U-shaped coil segment 4′ is constructed by curving the flat wire into a U shape to form a pair of legs 41′, 41′ and the head 42′ which joins the two legs 41′, 41′; and by curving the two legs 41′, 41′ so that tip ends (lower end) of the two legs 41′, 41′ are spaced from each other in the normal line direction (the circumferential direction in FIG. 10) with respect to a plane including the extending direction of the head 42′. The legs 41′ of each flat wire of the coil segment 4′ positioned in the slot 2a′ are disposed to be aligned in a row in the radial direction of the stator core 2′.
However, in the conventional coil end structure, the confronting surfaces of the flat wires at the coil end are different from the confronting surfaces of the flat wires in the slot, respectively. Therefore, it is easy for a corner portion of a flat wire to have a contact with an adjacent flat wire at the coil end, and thereby, there occurs a problem that an insulation coating of the flat wire may be peeled due to such effects as rotation vibrations or the like from the rotating electric machine.